Permission denied writing compile.elixir

Questions / Help Build debugging
1

I’m trying to deploy to fly.io for the first time. The ‘flyctl deploy’ command succeeds, but the app status is stopped and ‘flyctl logs’ shows the following error over and over:

[info]** (File.Error) could not write to file "/workspace/_build/prod/lib/XXXXXXX/.mix/compile.elixir": permission denied
[info]    (elixir 1.16.1) lib/file.ex:1143: File.write!/3
[info]    (mix 1.16.1) lib/mix/compilers/elixir.ex:905: Mix.Compilers.Elixir.write_manifest/8
[info]    (mix 1.16.1) lib/mix/compilers/elixir.ex:230: Mix.Compilers.Elixir.compile/7
[info]    (mix 1.16.1) lib/mix/state.ex:15: Mix.State.lock/2
[info]    (mix 1.16.1) lib/mix/task.ex:478: anonymous fn/3 in Mix.Task.run_task/5
[info]    (mix 1.16.1) lib/mix/tasks/compile.all.ex:124: Mix.Tasks.Compile.All.run_compiler/2
[info]    (mix 1.16.1) lib/mix/tasks/compile.all.ex:104: Mix.Tasks.Compile.All.compile/4
[info]    (mix 1.16.1) lib/mix/tasks/compile.all.ex:93: Mix.Tasks.Compile.All.with_logger_app/2
[info] INFO Main child exited normally with code: 1
[info] WARN Reaped child process with pid: 375 and signal: SIGUSR1, core dumped? false
[info] INFO Starting clean up.
[info] WARN hallpass exited, pid: 307, status: signal: 15 (SIGTERM)

It’s an Elixir app, but not Phoenix. I don’t have a Dockerfile, so I guess it’s auto-generating one but I don’t know how to see that.

Would appreciate if anyone can help with debugging this.

2

I just had this problem, and I just decided to create my own Dockerfile:

  • elixir_buildpack.config: You can remove it

  • fly.toml:

app = <app>
primary_region = <region>

[build]

[http_service]
  internal_port = 8080
  force_https = true
  auto_stop_machines = false
  auto_start_machines = false
  min_machines_running = 0
  processes = ['app']

[[vm]]
  size = <size>
  • Dockerfile
FROM hexpm/elixir:1.16.2-erlang-26.2.3-alpine-3.19.1 as base

RUN mkdir /app
WORKDIR /app

RUN apk --no-cache add g++ make git && mix local.hex --force && mix local.rebar --force

FROM base as test
COPY . /app

FROM base AS app_builder
ENV MIX_ENV=prod

# copy only deps-related files
COPY mix.exs mix.lock ./
COPY config config
RUN mix deps.get --only $MIX_ENV
COPY config/config.exs config/${MIX_ENV}.exs config/
RUN mix deps.compile
# at this point we should have a valid reusable built cache that only changes
# when either deps or config/{config,prod}.exs change

COPY priv priv
COPY lib lib
COPY config/runtime.exs config/
# COPY rel rel # could contain rel/vm.args.eex, rel/remote.vm.args.eex, and rel/env.sh.eex
RUN mix release

FROM alpine:3.19.1 as app

RUN apk add --no-cache bash openssl libgcc libstdc++ ncurses-libs

RUN adduser -D app
COPY --from=app_builder /app/_build .
RUN chown -R app:app /prod
USER app
CMD ["./prod/rel/<app_name>/bin/<app_name>", "start"]
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